This invention relates to fender piles and fendering systems, and more particularly to prestressed concrete fender piles having limited prestressing to allow for greater elasticity in bending and greater energy absorption.
Fender systems are used to protect waterfront piers, wharves, docks, and the like from the hazards of ship mooring and berthing. Berthing facilities and ships are subjected to various types of contact and loading during the mooring process or during berthing periods. Contacts between ship and fender system may be in the form of heavy impact, abrasive action from vessels, or direct pressure. Such contacts may cause extensive damage to the ship and to the pier structure if suitable means are not employed to counteract them. Fender piles are a key element developed for this purpose. Impact energy upon a fender pile is absorbed by deflection. Energy-absorption capacity depends on size, length, penetration, and material of the pile, and is determined on the basis of internal strain-energy characteristics. Fender systems are a troublesome and expensive high maintenance item for port operators because they are subject to frequent damage. A key to the performance of the fender system is the line of fender piles which guard a pier, receive the loads from the impact of ships, and distribute attenuated reactions to the seafloor soil and to appropriate locations on the pier.
More conventional fender piles are made from steel or timber. On a system basis, a large energy-absorbing rubber fender is required in a steel system to absorb ship impact energy, and steel is highly subject to rust and corrosion. Timber systems, on the other hand, are very good energy absorbers, but the total energy that timber pile can absorb is severely limited.
To overcome the constraints of steel and timber pile systems, prestressed concrete fender piles were developed that, on a pile-for-pile basis, can absorb significantly more energy than either steel or timber piles. In addition, using the prestressed concrete fender piles of the present invention, a prestressed concrete fender system is more cost effective than a more conventional fender system made from steel or timber piles. In addition to surpassing conventional steel and timber piles in terms of economics and energy absorption, the prestressed concrete piles of this invention also surpass in durability.